Tubing.



E. T. GREENFIELD.

TUBING.

APPLIOATION FILED JUNE 11,1906.

919,001 Patented Apr. 20, 1909.

WITNESSES lNVENTOR ATTORNEY tion.

UNITED STATES PATENT OFFICE.

EDWIN T. GREENFIELD, OF KIAMESHA, NEW YORK.

TUBING.

convolution overlapping that of the next adj acent one.

The object of the invention is to provide an improved tubing of this character and one which, though useful in many and widely different ways, is of particularntility as piping for a fluid under pressure, as forinstance, steam or compressed air. Such spirally-formed tubing has been adapted for this purpose heretofore by the provision of a gasket of compressible material between the overlapping portions of adjacent spirals in order topreclude leakage-of the'air or steam at the joints between the spirals. In all of these tubings, the strip from which the tube is formed has been curved laterally to provide for an interlock between adj acent irals and flexibility of the tubing has been s 0 tained by permitting each. spiral to move relatively to the adjacent spiral, until the into engagement.

interlocking parts of the two spiral came I have found that 1 the best results are obtained, particularly where the tubing is used as piping -forsteam or compressed air, when the maximum flexure of the tubing is somewhat limited since ex cessive bending isapt to open seams at the.

joints between the spirals through which .the

fluid may escape. My invention contemplates the provision of means for precluding such excessive flexing of the tubing and, in the preferred form of my invention, I ac- 1 complish this'by the employment of a tube concentric with and in'closing the tube carrying the, fluid and so constructed that" it cannot be bent more than a predetermined amount, which amount is such that in makingthe maximum bend, the spirals of the inner tube will not be moved relatively .so much as to open seams and permit leakage between them. The strip from which the inner tube is formed is given a peculiar transverse curvature and a plurality of asketsare spirally formed therewith in poc ets arranged to receive them so that leakage of Specification of Letters Patent.

1 Application filed J une 11,

Patented April 20, 1909. 190 Serial No. 831,131.

air or steam from the tube is reduced to a minimum whether the tube be straight or curved.

I will describe my invention in connection show the preferred embodiment thereofand in which- Figure 1 is a sectional elevation of a piece of the tubing bent to the arc of a circle and Fig. 2 is an enlarged sectional. view of a portion thereof.

Referring to these drawings, thetubing consists of two concentric tubes each constrip. The strip for each tube is curved instance by means of't'he mechanism shown in Patent Number 630,503 heretofore granted to me. The strip A for the inner tube may have a main portion a and on either side thereof a'flange a and a beyond the flange a is an outwardly curved portion a and beyond the flange a is a depressed portion a a flange a and an inwardly curved portion a. Such strip-is spirally-formed into a tube owit-h eachspiral overlapping a portion of the next adjacent spiral and com- .wound thereon, the gasket 0 lying between the outwardly curved portion a of one spiral and the depressed portion a of the next and the gasket 0 between the inwardly curved portion (2 of one spiral and the main portion a of the next. The strip is wound very tightly to form the tube, the gaskets being compressed by the parts between which they are confined, so that practically no leakage of air orsteam from the tube would occur. Ample flexibility is provided as each spiral can move relatively to the adjacent one. Concentric with and in closing this tube is an outer tube formed of a strip B. This strip has abody portion 1), flanges b and b at the sides thereof and, beyond the flange b", a depressed portion and flange b. The stripis formed spirally with each spiral overlapping a portion of the adjacent one, the edge of flange b of b of the next. This tube is also flexible as the edge of each flangeb' can move over the portion b and such movement of the spirals relatively is limited by the engagement of the 'flan'ges'b and b. The distance between the flanges b and b when thetube with the accompanying drawings i-which sisting of successive spirals of a metallic pressible gaskets c and c are simultaneously one spiral bearing on the depressed portion transversely in any suitable manner, as for is straight, isless than the distance between I 4 the flanges a and a of the tube A so that when the piping as a' Whole is bent the flanges Z) and b of the spirals of the outer tube engage and prevent further flexing while the flanges a and a of the spirals of the inner tube are still separated. This condition is illustrated in "Fig. 1 in which the tube-is shown as bent to the maximum flexure permissible. It will be seen that the interlocking flanges of the outer tube are in contact and therefore further relative movement is precluded while the interlocking flanges of the inner tube are out of contact.

Having described my invention what I claim as new and desire to secure by Letters Patent is: v

A tubing comprising the combination of a Water-tight tube consisting .of a series of metallic, interlocking, relatively-movable spirals having a gasket between the adj acent spirals thereof and a second tube inelosing said first-named tube and also consisting of a series of metallic, interloekin relativelymovable spirals, said second tu being arranged to limit the flexure of the tubing in the direction of its length by being so constructed that when the tubing is flexed in the direction of its length the interlocking parts on the outer tube come into engagement to reelude further flexure while the interlocking parts of the inner tube are separated, substantially as set forth.

This specification signed and witnessed this 8th day of June, 1906.

EDWIN T. GREENFIELD. Witnesses:

WILLIAM T. RUTH, CHAS. E. WILSON. 

